The effect of electrode surface modification and cathode overpotential on deposit characteristics in aluminum electrorefining using EMIC-AlCl_3 ionic liquid electrolyte

摘要

Electrorefining of aluminum alloy was investigated using AlCl_3 and 1-ethyl-3-methyl-imidazolium chloride (EMIC) (molar ratio AlCl-3: EMIC = 1.65:1) ionic liquid electrolyte on copper and aluminum cathodes at temperature of 90 ± 3℃ and cell voltage of 1.5 V. The effect of electrode surface modification and cathode overpotential on deposit characteristics of aluminum was investigated. The surface modification of electrodes reduced the dendritic depositions of aluminum. It was also observed that cathodic overpotentials obtained from experiments using modified electrodes are significantly lower than those of unmodified electrodes. A non-dendritic deposit of aluminum was observed even after prolonged electrorefining of 25 h. Pure aluminum deposits were obtained for all experiments with the current efficiencies in the range of 94-99%.